This is the 13530th most frequent Russian word.
настоящей
The Russian word "настоящей" means "real," "genuine," or "true" (feminine form, instrumental or dative case).
Here, "настоящей" is used as an adjective to describe "дружбой" (instrumental case), indicating sincerity or authenticity.
Это была настоящей дружбой.
It was true friendship.
In this sentence, "настоящей" describes "грани" (locative case), suggesting a genuine or actual state.
Мы находимся на настоящей грани перемен.
We stand at the real brink of change.
Here, "настоящей" is used to qualify "легендой" (instrumental case), emphasizing authenticity or unquestionable notoriety.